# **Biohybrid Robots: The Promise of Cyborg Technology?**
The combination of biological and synthetic elements in robotics has long captivated the imaginations of scientists and engineers. Biohybrid robots, which merge living tissues with artificial materials, represent a thrilling progression toward this goal. Nevertheless, in spite of notable advancements, the technology still confronts significant hurdles. A recent development from researchers at Tokyo University underscores both the prospects and the constraints of biohybrid robotics.
## **What Are Biohybrid Robots?**
Biohybrid robots blend biological components—like muscles, plant tissues, or even fungi—with synthetic frameworks. These robots aim to leverage the inherent efficiency, adaptability, and flexibility of biological materials while enjoying the precision and durability offered by artificial substances.
However, a primary challenge in biohybrid robotics is maintaining the vitality and functionality of the biological segments. Up to this point, most biohybrid robots have been small and uncomplicated, generally measuring no more than a few centimeters, with limited movement capabilities.
## **A Breakthrough in Biohybrid Robotics**
A group spearheaded by Professor Shoji Takeuchi at Tokyo University has achieved a notable milestone by crafting a full-sized, 18 cm-long biohybrid robotic hand. This hand, designed to replicate human anatomy, is powered by lab-cultivated human muscles. The research signifies a pivotal advancement in scaling biohybrid robots.
### **The Challenge of Keeping Muscles Alive**
One significant barrier in the creation of larger biohybrid robots is necrosis, the decay of cells resulting from inadequate oxygen and nutrition. In living organisms, blood vessels carry these vital resources to muscle tissues. However, lab-cultivated muscles do not possess these vascular systems, making it challenging to sustain them when they exceed a certain thickness.
To address this, Takeuchi’s team devised an innovative method: **MuMuTAs (Multiple Muscle Tissue Actuators)**. These are cylindrical clusters of muscle fibers made by rolling thin muscle sheets—analogous to preparing sushi rolls. This approach guarantees that all muscle cells receive sufficient oxygen and nutrients, preventing necrosis.
## **How the Biohybrid Hand Works**
The robotic hand created by Takeuchi’s team features five fingers, each with three joints. The hand is constructed from 3D-printed plastic and is kept in a liquid medium to maintain muscle vitality.
Each finger is operated by a MuMuTA, which contracts in response to electrical impulses. The intensity of the contraction can be adjusted by changing the applied voltage. By selectively activating different MuMuTAs, the hand can execute a range of gestures, including those used in the rock-paper-scissors game. It can also handle small items, such as a pipette.
## **Limitations and Challenges**
Despite its achievements, the biohybrid hand presents several limitations:
1. **One-Way Movement** – The fingers are capable of moving solely in one direction. In human hands, opposing muscles work collaboratively to enable fingers to move back and forth. The robotic hand depends on the buoyancy of the liquid medium to restore fingers to their initial position. A possible remedy is to introduce elastic materials at the joints or integrate additional MuMuTAs for bidirectional mobility.
2. **Dependence on Liquid Suspension** – The hand is incapable of operating outside a liquid environment. Future improvements must incorporate artificial nutrient delivery systems to sustain the muscles in dry conditions.
3. **Muscle Fatigue** – The biohybrid muscles fatigue rapidly. After approximately 10 minutes of usage, the hand requires an hour of rest before regaining functionality. This occurs because lab-grown muscles are notably weaker than natural human muscles.
## **The Future of Biohybrid Robotics**
One potential solution for muscle fatigue is **exercise**. Just as natural muscles strengthen and resist fatigue through repeated use, lab-grown muscles may also improve with regular contractions. An additional approach could involve utilizing chemical growth factors to boost muscle strength.
Although biohybrid robotics remains in its nascent phase, the endeavors of Takeuchi and his team represent a significant leap forward. If researchers can surmount the current challenges, biohybrid robots may transform domains such as prosthetics, medical robotics, and even space exploration.
For the time being, the aspiration for fully functional cyborg technology remains an aspiration. However, with ongoing research and innovation, the boundary between biology and robotics may soon become even more indistinct.
### **Reference:**
Takeuchi’s research on biohybrid robotic hands is published in *Science Robotics*: [http://dx.doi.org/10.1126/scirobotics.adr5512](http://dx.doi.org/10.1126/scirobotics.adr5512)
